本文選題：多軸疲勞 + 不確定性��； 參考：《湖南大學(xué)》2014年碩士論文

【摘要】：在實(shí)際工程問題中存在著大量的疲勞現(xiàn)象，且大部分情況下零部件所承受的載荷為多軸循環(huán)載荷，因而如何對多軸循環(huán)加載下的零部件進(jìn)行更好的壽命預(yù)測成為疲勞領(lǐng)域內(nèi)的熱點(diǎn)研究之一。目前，國內(nèi)外對于多軸疲勞的研究雖然有了一些進(jìn)展，但由于多軸疲勞本身的復(fù)雜性，如今在理論和試驗(yàn)研究方面還不成熟，，對金屬在多軸載荷下的疲勞壽命預(yù)測進(jìn)行相關(guān)研究具有重要的理論和工程意義。本文在多軸疲勞壽命預(yù)測及其可靠性方面進(jìn)行了一些嘗試，相關(guān)研究工作如下： （1）基于現(xiàn)有的多軸疲勞準(zhǔn)則，運(yùn)用模糊理論，建立了一種多軸高周疲勞模糊準(zhǔn)則。并結(jié)合材料的S-N曲線，可獲得不同可靠度P下的多軸疲勞P-S-N曲線。該方法能夠在一定程度上反映疲勞試驗(yàn)數(shù)據(jù)的分散性與不確定性。 （2）提出了一種能夠考慮加載路徑對多軸低周疲勞壽命影響的路徑載荷因子。借助該因子，構(gòu)建了兩種多軸低周疲勞壽命預(yù)測模型(拉伸型與剪切型)，使得預(yù)測模型能夠較好地考慮應(yīng)力比和相位角的影響。最后，運(yùn)用大量試驗(yàn)數(shù)據(jù)對兩種模型進(jìn)行了驗(yàn)證。 （3）基于等壽命曲線的思想，提出了一種新的多軸高周疲勞壽命預(yù)測方法。該方法在一定程度上考慮了多軸比例加載與材料固有屬性之間的關(guān)系，而不是單純依靠材料的單軸疲勞強(qiáng)度與剪切疲勞強(qiáng)度來預(yù)測比例加載下的結(jié)果。不僅如此，該方法還利用一組多軸非比例加載下的試驗(yàn)數(shù)據(jù)來考慮了不同材料之間對非比例的敏感程度。
[Abstract]:There is a large number of fatigue phenomena in practical engineering problems, and in most cases, the load of components is multiaxial cyclic load. Therefore, how to better predict the life of the components under multiaxial cyclic loading has become one of the hot topics in the field of fatigue. At present, although there has been some progress in the study of multiaxial fatigue at home and abroad, due to the complexity of multiaxial fatigue itself, the theoretical and experimental research is still immature. It is of great theoretical and engineering significance to study the prediction of fatigue life of metals under multiaxial loads. In this paper, some attempts have been made on the prediction of multiaxial fatigue life and its reliability. The related research work is as follows: 1) based on the existing multiaxial fatigue criterion and fuzzy theory, a multiaxial high cycle fatigue fuzzy criterion is established. The multiaxial fatigue P-S-N curves with different reliability P can be obtained by combining the S-N curves of the materials. This method can reflect the dispersion and uncertainty of fatigue test data to some extent. (2) A path load factor which can consider the effect of loading path on multiaxial low cycle fatigue life is proposed. With the help of this factor, two kinds of multiaxial low cycle fatigue life prediction models (tensile type and shear type) are constructed, which can better consider the influence of stress ratio and phase angle. Finally, a large number of experimental data are used to verify the two models. A new multiaxial high cycle fatigue life prediction method is proposed based on the idea of equal life curve. To some extent, this method considers the relationship between multiaxial proportional loading and intrinsic properties of materials, rather than simply relying on uniaxial fatigue strength and shear fatigue strength to predict the results under proportional loading. Not only that, but also a set of experimental data under multiaxial and non-proportional loading is used to consider the non-proportional sensitivity of different materials.
【學(xué)位授予單位】：湖南大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TH133.2

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本文編號：1864210